Figure 1 - available via license: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Content may be subject to copyright.
shows the schematic diagram of a fast-fill refueling station. The compressor on/off status is set through switch u. When the compressor is turned on, compressed gas flows into the cascade storage through
Source publication
Compressed natural gas (CNG) is one of the growing alternatives to liquid petroleum fuels for propulsion of motor vehicles. Lower greenhouse gas emissions as well as increased durability of vehicle engines are the main properties of CNG that make it a better alternative to petrol and diesel. CNG refueling infrastructure is vital to the expansion of...
Citations
... The results show optimal parameters for energy consumption and the payback period of the investment. Kagiri et al. [29] carried out an energy and economic optimization of a natural gas decompression station to reduce operating costs. The results show benefits from optimizing equipment parameters and ideal operating ranges, as well as potential savings of 59.28% in system operating costs after optimization. ...
Natural gas stations require a preheating stage to prevent the formation of hydrates inside of them provoked by a sudden decompression process of the natural gas. The preheating process has been investigated to improve efficiency and to reduce costs as well. This work studies the behavior of a natural gas decompression station with a first-stage preheating process using a vortex tube and a geothermal heat exchanger, followed by a second stage involving a water bath heater (heating vat). An energetic, exergetic, and exergoeconomic study has been carried out based on a mathematical model and the theory of exergetic cost, obtaining key thermodynamic and thermoeconomic variables, including exergy flows and equipment costs. A heat flow of 26.41 kW was obtained in the geothermal preheating stage; meanwhile, a 60.43 kW heat flow was obtained in the heating vat. The results showed a saving in station fuel using only 2.046% of the natural gas in the system at the second preheating stage. Also, the system was optimized, obtaining a 15.73% reduction in the decompressed natural gas cost. These findings show the possibility of implementing these systems in zones with many geothermal resources to reach a constant, profitable natural gas supply in areas where a pipeline network does not exist.
... It is therefore very important that the plans for the natural gases infrastructure expansions get real so that suppliers and operators can invest in proper natural gases products to be used effectively in transportation, industry and domestic sectors. Currently, at CNG stations, gas flow to the vehicle is measured by mass for sale with dispensers designed with compensation for temperature variations to ensure accurate quantities are delivered to the tank [6]. ...
Energy consumption and its environmental impact are now among the most challenging problems in most developing cities. The common sources of energy used as the fuel in transportation sector include gasoline, diesel, natural gas, propane, biofuels, electricity, coal, and hydrogen. However, in Tanzania, diesel and gasoline are still the dominant source of energy used by public and private vehicles. We have experienced significant efforts of converting conventional vehicles (gasoline engines) to operate on Compressed Natural Gas (CNG) or on hybrid system (gasoline and natural gas) as an alternative source of energy in Tanzania. The CNG is considered as cleaner combustion energy used as a vehicular fuel alternative to gasoline or diesel. In this chapter, the amount of energy consumption from the fuel combustion, the impact of environmental health (toxicity gas emission), the cost of fuel used by the transit buses in terms of fuel energy consumption, and driving profile are discussed. The scope of this work is based on the total energy contained in the fuel only. The ability of the engine to transform the available energy from the fuel into useful work power (efficiency) is left to the designers and manufacturers.
... They also suggest that the effect of abrasion and wear will decrease in compressors that will operate at these times. Kagiri et al. [7], in their study, stated that the economical operation of CNG fuel filling stations will reduce the cost of fuel delivery and it will benefit consumers and it will be determined that the timing of the compressors in the current CNG fuel filling stations will be optimal and the energy costs will be reduced according to the electricity tariff used. Kagiri et al. [8], in their study, proposed optimum energy management strategies for CNG refueling station operations. ...
In line with the increase in the world population, natural gas, which has an
increasing share in fossil fuels, is nowadays transported throughout
pipelines in the form of liquefied natural gas (LNG) and compressed natural
gas (CNG). Natural gas is preferred to be transported with CNG in terms of
optimum cost. CNG is reduced to a volume of 1/250 at 200 bar pressure in
filling facilities and is transported to multi-element gas containers or gas
tankers where pipelines do not reach. Although the highest cost for these
plants seems to be gas transportation costs, the design, infrastructure and
operational gaps, especially in plant management of the filling facilities
constitute the costs that are not significantly visible. In parallel with
the costs incurred, in this study, a pre-cooling process was actively
applied for cost-based improvement in a bulk CNG filling facility, while
operational optimization was aimed passively. The filling process of the
facility in 2016 was examined according to real data and pre-cooling was
made in 2017 by adding a “chiller” to the filling process to increase the
filling rate to tankers. Thanks to the precooling in 2017, the filling
amount made to tankers increased by %7.23. In 2018, the filling process was
analyzed in detail according to the data of 2017 and the factors affecting
the filling rate were determined. According to these factors, the filling
operation has been optimized on a cost basis. Filling operations in 2018
have been optimized for factors varying from month to month and even day,
such as; temperature conditions, filling method, the structure of gas
tankers and filling platforms, ie the effect of the material used, personnel
effect and the filling rate of machines like chiller, compressor. After
optimization, the amount of filling made in 2018 increased by %4.36 compared
to 2017.
... During operational tests, natural gas demand m 3 /h and energy consumption kW/h were investigated. Based on test results, the following costs were determined: (i) for one full refueling; (ii) for one hour of HRS operation in different conditions; and (iii) for net cost of 1 Nm 3 CNG [27]. ...
Compressed natural gas can be globally used as fuel for combustion engines to reduce CO2 emission without negative impact on economy. Lack of refueling infrastructure is one of reason why NGVs shares only ~1.6% in total vehicle fleet worldwide. Operational tests of CNG home fast refueling station were performed to investigate: (i) natural gas demand, m3/h; (ii) energy consumption, kW/h; and (iii) total cost of one refueling. Two scenarios for operational tests were developed to monitor and collect data. Safety tests for leakage, fill pressure change, interrupted power and gas supply, temperature, and unexpected failures were performed. This article present results of operational and safety tests of compressed natural gas home, fast refueling station (CNG-HRS) based on one stage hydraulic compressor. The average duration of HRS full operating cycle was 7 h and 32 min (buffering and refueling mode). The average electric energy and natural gas consumption for one full cycle was 5.52 kWh and 7.5 m3, respectively. Safety tests results for leakage, fill pressure change, interrupted power and gas supply, temperature and unexpected failures demonstrated valid operation of HRS which positively affects the general safety level. To compare HRS with large scale CNG refueling infrastructure the costs of 1 Nm3 CNG was estimated for both solutions. Results shows that home refueling appliance might be become a solution for filling the gap in CNG refueling infrastructure.
... In [12,28], a strategy to minimise electricity cost for a CNG fast fill station was undertaken for a station operating under a time-of-use (TOU) electricity tariff. The station was modelled as a mass balance system where the storage was modelled as a single reservoir with an outflow from a known demand profile and inflow from an optimally scheduled compressor. ...
Compressed natural gas stations serve customers who have chosen compressed natural gas powered vehicles as an alternative to diesel and petrol based ones, for cost or environmental reasons. The interaction between the compressed natural gas station and electricity grid requires an energy management strategy to minimise a significant component of the operating costs of the station where demand response programs exist. Such a strategy when enhanced through integration with a control strategy for optimising gas delivery can raise the appeal of the compressed natural gas, which is associated with reduced criteria air pollutants. A hierarchical operation optimisation approach adopted in this study seeks to achieve energy cost reduction for a compressed natural gas station in a time-of-use electricity tariff environment as well as increase the vehicle fuelling efficiency. This is achieved by optimally controlling the gas dispenser and priority panel valve function under an optimised schedule of compressor operation. The results show that electricity cost savings of up to 60.08% are achieved in the upper layer optimisation while meeting vehicle gas demand over the control horizon. Further, a reduction in filling times by an average of 16.92 s is achieved through a lower layer model predictive control of the pressure-ratio-dependent fuelling process.
... Research investigating operation efficiency is still scarce when it comes to energy cost incurred during compressor cycling. The researchers in this work have previously reported results for a finite horizon open loop control strategy for compressor scheduling to minimize electricity costs in a 24 hour period [8]. ...
In order to lower the cost of gas delivery to consumers who use compressed natural gas to propel their vehicles, operators of compressed natural gas stations in locations where electricity is sold under time-of-use tariff pricing can adopt station operation strategies that result in lower energy costs to secure their revenue. While finite horizon open loop control has shown the potential for significant savings on electricity costs while meeting the gas demand profile, receding horizon control can increase the robustness of the scheduling optimization by delivering a convergent solution for continuous operation of the plant. The present work shows the performance of the compressed natural gas station when the receding horizon control strategy is implemented achieving savings of up to 56.7% and a solution for continuous operation.
... Through investigation, CNG is the most promising alternative fuel because it is affordable, it has cleaner burning characteristics compare to conventional fuels and it is renewable. It is also has the property of increase the durability of the vehicle engines [2]. CNG is a cleaner fuel compared to any other conventional fuels [17]. ...
Injection timing gives great impacts on the performance characteristics of the internal combustion engine (ICE) fuelled by hydrogen enriched compressed natural gas engine employing exhaust gas recirculation (DI-HCNG-EGR). There are two main types of injection timings viz: early and late injection timing. However, the different injection timings have different effect on performance characteristics of internal combustion engine which are difficult to understand such as the increase or decrease in brake torque (BT), Brake specific energy consumption (BSEC) and brake thermal efficiency (BTE).Therefore, the impact of injection timing (early and late injection timing) on internal combustion engine (ICE) fuelled by hydrogen enriched compressed natural gas engine employing exhaust gas recirculation (DI-HCNG-EGR) is relatively unclear. The primary focus of this research is to experimentally study the effect of the early and late injection timing on performance characteristics of the internal combustion engine fuelled by hydrogen enriched compressed natural gas engine employing exhaust gas recirculation (i.e. DI-HCNG-EGR). The experiment was conducted at part throttle, constant engine speed (i.e. 200rpm) with different fractions of hydrogen (H 2) (i.e. 0-46% by volume) and EGR rates (i.e. 0-30% by mass). The results showed that for a specified percentage of EGR rates, early injection timing gives better performance characteristics (i.e. higher brake torque, lower BSEC and higher BTE) as compared to late injection timing in DI-HCNG-EGR. In addition, the results also showed the percentage of hydrogen gas that guarantee the best performance characteristics in DI-HCNG-EGR is approximately lies between 0%-20%. Thus, it can be technically concluded that early injection timing is better injection strategy that guarantee a better performance characteristics in DI-HCNG-EGR as compared to late injection timing. Note well-For the purpose of this study, early injection timing was taken to be 300° before top dead centre (BTDC) and late injection timing was taken to be 120° before top dead centre (BTDC) on the valve timing diagram.
... Kagiri, Zhang, and Xia consider the CNG production costs and find out that when using fast fill cascade station it is possible to reduce electricity costs to around 60% if the compressor work schedule is improved in a time-of-use electricity tariff environment. It can be used to reduce the fuel end price and in this way to stimulate consumers to use widely ecological fuel which would facilitate the reduction of harmful emissions [53]. The focus of the research is just the energy efficiency of the compression operations. ...
Building a competitive and resource-efficient transportation system involves the achievement of a number of ambitious goals. Two of the main instruments in the European transportation policy in this field address the significant reduction of GHG emissions and oil dependency in transportation. Alternative fuels and compressed natural gas (CNG) in particular have huge potential for achieving these goals. The main problem that limits its wide utilization is related to the insufficient number of CNG refueling stations, especially along highways and routes from the core TEN-T network where no gas pipelines are available. Therefore, the aim of this research is to study a possible solution to building daughter CNG refueling stations which can be used as basis for formulating some recommendations for their accelerated construction along TEN-T core network as well as providing some initial knowledge to be used later for more comprehensive research. The research is based on the case-study method, which allows the presentation of the described best practice. The process of data collection is based on semi-structured interviews, study of normative documents, observation of daily sales and direct observations which were processed with the help of qualitative and quantitative methods for time series analysis—trend and seasonal component as well as descriptive statistics tools. Scientific literature and research as well as secondary data provided by international institutions are also used.
